Scholarlink

<p>Prokaryotic Argonaute proteins (pAgos) are nucleic acid-guided endonucleases with diverse functions. <i>Mucilaginibacter paludis</i> Argonaute (MbpAgo) is unusual in using guide DNA (gDNA) to cleave target RNA (tgRNA), but the structural basis for this activity has been unclear. Here we present cryo-electron microscopy structures of MbpAgo in apo, binary, and ternary states at up to 2.55 Å resolution. The apo structure reveals a conserved bilobal scaffold with unique insertions in the PIWI and MID domains that stabilize the catalytic conformation. Upon gDNA binding, MbpAgo forms a dimer stabilized by multiple protein-protein interfaces and an auxiliary nucleic acid-like density bridging the PAZ-MID lobes. The auxiliary nucleic acid interactions coordinate gDNA binding and dimer stabilization to support MbpAgo activity, with dimerization becoming particularly important for efficient cleavage with double-stranded DNA (dsDNA) guides. Binding of tgRNA induces a DNA-RNA hybrid duplex and conformational changes that destabilize the dimer, reverting MbpAgo to an active monomer capable of cleaving structured viral RNAs such as the SARS-CoV-2 5′UTR and HIV-1 CES. These findings suggest a dynamic monomer-dimer transition as both the regulatory mechanism of MbpAgo and an evolutionary adaptation for processing dsDNA-derived guides, providing a structural framework for programmable RNA targeting.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Dynamic monomer-dimer transition regulates DNA-guided RNA cleavage by MbpAgo

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年5月4日

查看全文
  • Xiaolong Zhao,
  • Wen Yang,
  • Linfeng An,
  • Lu Chen,
  • Jun Xiao,
  • Kaiming Zhang,
  • Shanshan Li

摘要

Prokaryotic Argonaute proteins (pAgos) are nucleic acid-guided endonucleases with diverse functions. Mucilaginibacter paludis Argonaute (MbpAgo) is unusual in using guide DNA (gDNA) to cleave target RNA (tgRNA), but the structural basis for this activity has been unclear. Here we present cryo-electron microscopy structures of MbpAgo in apo, binary, and ternary states at up to 2.55 Å resolution. The apo structure reveals a conserved bilobal scaffold with unique insertions in the PIWI and MID domains that stabilize the catalytic conformation. Upon gDNA binding, MbpAgo forms a dimer stabilized by multiple protein-protein interfaces and an auxiliary nucleic acid-like density bridging the PAZ-MID lobes. The auxiliary nucleic acid interactions coordinate gDNA binding and dimer stabilization to support MbpAgo activity, with dimerization becoming particularly important for efficient cleavage with double-stranded DNA (dsDNA) guides. Binding of tgRNA induces a DNA-RNA hybrid duplex and conformational changes that destabilize the dimer, reverting MbpAgo to an active monomer capable of cleaving structured viral RNAs such as the SARS-CoV-2 5′UTR and HIV-1 CES. These findings suggest a dynamic monomer-dimer transition as both the regulatory mechanism of MbpAgo and an evolutionary adaptation for processing dsDNA-derived guides, providing a structural framework for programmable RNA targeting.